In this specification, where a document, act or item of knowledge is referred to or discussed, this reference or discussion is not an admission that the document, act or item of knowledge or any combination thereof was at the priority date:                (i) part of common general knowledge; or        (ii) known to be relevant to an attempt to solve any problem with which this specification is concerned.        
With world crude and petroleum oil prices being normally fairly volatile, due to a wide variety of market and politically related supply & demand factors, the more expensive oil production from these unconventional sources is economically uncertain. Furthermore, the production of oil and its transport, as well as the combustion of petroleum-derived fuels in internal combustion engines, is a major source of CO2, CH4 and NOx production. These are classified as greenhouse gases, i.e. gases that trap heat in the atmosphere, which are responsible for the global climate change. To alleviate these concerns significant effort has been devoted to the production of fuels from renewables. Thereby the term renewables refers generally to lignocellulosic materials, i.e. biomass derived mainly from higher plants or its processed residues (e.g. paper, pulp, lignin waste), and its components being cellulose, hemicellulose and lignin.
The conversion of biomass into fuels is commonly practised in biorefineries. The UK's National Non-Food Crops Centre (NNFCC) defines a biorefinery as a manufacturing site involved in the refining of biomass material to yield purified materials and molecules. This conversion can be achieved using biological or thermochemical processing or a mixture of both. The fuel or fuel additives produced by biorefineries concern bio-alcohols such as bioethanol and biobutanol. First generation biorefineries derive these from starchy products, such as corn kernels, because starches are easy to break down into the sugars needed to make bio-alcohols.
Over recent years, concern on the use of food-for-fuel has shifted attention to second generation biorefineries which use non-food lignocellulosic material. These contain tough cellulose fibres which are much harder to process and break down into fermentable sugars. The production of bio-alcohols from lignocellulosic biomass for fuel applications presents a number of financial challenges due to low profit margins. Also, second generation biorefineries produce substantial amounts of waste lignin for which no ready high-value applications are known.
Waste lignin is defined as lignin-rich solid residues remaining after industrial high-temperature pre-treatment, with or without the presence of mineral acids, which deconstructs the densely packed cellulose fibres to bundles of polysaccharide chains that are more accessible to enzymatic hydrolysis. This pre-treatment is generally conducted at elevated temperature which is typically in the range 120.° to 240.° C.
The reaction mixture may then be passed to a simultaneous saccharification and fermentation (SSF) stage, involving both cellulolytic enzymes and yeast cells, in which the bulk of the polysaccharides are converted to bio-alcohols and carbon dioxide. Alternatively the enzyme-mediated saccharification and the yeast-based fermentation of the resulting monosaccharides may be conducted as separate consecutive process steps. In either case, the lignin component of the original lignocellulose remains as solid particles in suspension and is almost always found to contain significant quantities of residual saccharides that have resisted the action of the enzymes and the yeast. This solid material that can be collected using a belt press, or by other means is called ‘waste lignin’. A number of types of lignin exist amongst which are:                a) hydrolysis lignin comprising lignin residues remaining after industrial treatment, using mineral acids, deconstructing the cellulose fibres to more digestible saccharides, followed by an enzymatic treatment converting these saccharides into bio-alcohols; and        b) lignin resulting from the kraft or sulfite pulping processes.        
Part of this waste lignin can be used to burn as fuel supporting the biorefinery process.
Presently, significant research efforts are being devoted to the development of efficient depolymerisation processes of waste lignin to form typically aromatic products.
The invention is directed to a method for producing a high value platform chemical, “(1S, 5R)”-6,8-dioxabicyclo[3.2.1]oct-2-en-4-one, also known as (−)-levoglucosenone, and here abbreviated as LGE, from waste lignin.
LGE is one of the few molecules from sustainable sources with a market value able to compete with current non-renewables. LGE is a versatile molecule that can serve as a chiral intermediate to the synthesis of a wide range of pharmaceuticals.1 LGE can also be selectively isomerized into 5-hydroxymethylfurfural,2 hereafter abbreviated as 5-HMF, which is a valuable precursor for both fuels and pharmaceuticals. Recently, a range of patents describe the conversion of LGE to 1,6-hexanediol and 1,2,6-hexanetriol.3 These are key intermediates in the synthesis of 1,6-hexanediamine, caprolactone and caprolactam, which are used for the manufacturing of polyesters, polyamines and polyurethanes, representing multimillion tonne articles of commerce. Recently, it was also found that dihydro-LGE (dihydrolevoglucosenone) (Cyrene™) has great potential as a dipolar aprotic solvent with similar properties to N-methylpyrrolidone, commonly known as NMP, and N,N-dimethylformamide, commonly known as DMF.4 
Few processes exist to produce LGE from biomass, polysaccharides, or biomass derivatives and only one process has been operated on a semi-commercial scale.4 Most commonly phosphoric acid is used, but not limiting to, often in combination with a dipolar aprotic solvent such as sulfolane.5 Also, the use of ionic liquids has been found beneficial.6 Typically, all these methods require a high reaction temperature exceeding 250° C. A method was patented by Circa Group Ltd in which LGE is obtained from particulate lignocellulosic material using a polar organic liquid and a mineral acid, in the presence or absence of water, at high temperature.7 In the Circa patent the term “lignocellulosic material” and forms of the term “lignocellulosic material” refer to materials having a combined cellulose and hemicellulose content above 30% w/w.